Firefighters continue to battle blazes across California

San Francisco and Watsonville, Calif. — Gusty and unpredictable winds continue to vex California firefighters trying to protect hundreds of homes from a raging wildfire in Santa Cruz County.

The fire that began Wednesday evening of unknown causes had grown from roughly 30 acres to 6,800 acres Saturday morning, according to state fire officials, making it the county's largest fire in 20 years.

So far no homes have been damaged, but more than 250 houses in the densely wooded hills and canyons of the Santa Cruz Mountains remain threatened. About 2,400 residents are under mandatory evacuation orders.

The 570 California firefighters working the Lockheed Fire , named for its proximity to Lockheed Martin Space Systems campus, have managed to contain 30 percent of the blaze but are being challenged by both the wind and rough terrain – the hills along the coast are thick with pine trees and brush making the fire difficult to access.

California Assemblyman Bill Monning, whose district includes Santa Cruz County, said Saturday morning the fire line seemed to be holding.

"Each fire takes on its own personality," he says. "One thing that distinguished this Lockheed Fire is that this area hasn't burned for over 60 years. So it's burning really hot and spreading fast."

A battalion chief told the Associated Press that "as the brush ignites, it's like a fireworks explosion, and the sparks rain down where the ranch houses are."

On Friday afternoon dark smoke from the fire clouded the air around the beachside town of Santa Cruz and plumes extended some 50 miles across the central California coastline. An air quality advisory remains in effect.

The firefighter staging area at the Watsonville Fair Grounds, about 20 miles from Santa Cruz, has been converted into a tent city for crews who have come from across the state. The fair grounds is also being used to house evacuated livestock from the farms and ranches in and around the hill outside Santa Cruz.

On Friday afternoon Amelia Summitt, from Santa Cruz County Animal Services, was looking after more than 120 animals – horses, sheep, goats, and a few alpacas were among the herd – that had been evacuated from the fire.

Ms. Summitt says she wasn't sure if more animals would be coming. "Everything depends on the wind."

In northern California, officials have charged a 60-year-old woman for tossing out a lit cigarette that apparently started the so-called Coffin Fire in Trinity County. That blaze is nearly contained after it spread over 1,200 acres.